High energy axial flow transfer stage

ABSTRACT

Axial flow apparatus for transferring substantial energy to a fluid utilizing a stage having two sets of pluralities of blades secured to and extending radially from a rotor. The first set of energy adding blades, called the main blades, incorporates an airfoil section that is warped or twisted from its root at the rotor to its tip adjacent the housing. The airfoil shape and other design characteristics of the main blades may be conventional and of the type commonly found in axial flow pumps, blowers, and compressors. A second plurality of energy adding blades, which may be referred to as auxiliary blades, is provided and is positioned downstream from the main blades without intervening stationary vanes and may be located either directly behind corresponding main blades or may be circumferentially displaced forward or backward in the direction of blade travel. The leading edges of the auxiliary blades are angled with respect to, or are not parallel, to the trailing edges of the main blades. The blades are warped or twisted from a root cross section that exhibits a chord forming an angle of greater than 90* with the plane of rotation of the blades. The trailing edge of the auxiliary blades at the respective blade roots is thus placed away from the main blades and points into the direction of rotation.

llriited States Patent [191 [4 Feb. 18, 1975 Troller 1 HIGH ENERGY AXIAL FLOW TRANSFER STAGE [76] Inventor: Theodor H. Troller, Ava Banch,

Portal, Ariz. 85632 [22] Filed: Sept. 19, 1973 [21] Appl. No.: 398,654

Related US. Application Data [63] Continuation-impart of Ser. No. 183,413, Sept. 24,

1971, abandoned.

[52] US. Cl 415/194, 415/D1G. 1, 416/236 [51] Int. Cl. F04d 29/32 [58] Field of Search 415/D1G. 1, 213, 194;

[56] References Cited UNITED STATES PATENTS 1,744,709 1/1930 Moody 415/D1G. 1 1,836,860 12/1931 Moody 415/130 2,314,572 3/1943 Chitz 415/DIG. 1 2,576,700 11/1951 Schneider 415/DlG. 1 2,920,864 1/1960 Lee 415/D1G. 1 2,935,246 5/1960 Roy 4l5/DIG. 1 2,938,662 5/1960 Eckert et al. 415/D1G. 1 2,982,361 5/1961 Rosen 415/129 3,075,743 1/1963 Sheets 4l5/D1G. 1 3,112,866 12/1963 Fortescue.... 415/D1G. 1 3,128,939 4/1964 Szydlowski... 415/181 3,692,425 9/1972 Erwin 416/236 3,768,546 10/1973 Shipes 415/130 Primary ExaminrHenry F. Raduazo Attorney, Agent, or Firm-Cahill, Sutton & Thomas [57 ABSTRACT Axial flow apparatus for transferring substantial en ergy to a fluid utilizing a stage having two sets of pluralities of blades secured to and. extending radially from a rotor, The first set of energy adding blades, called the main blades, incorporates an airfoil section that is warped or twisted from its root at the rotor to its tip adjacent the housing. The airfoil shape and other design characteristics of the :main blades may be conventional and of the type commonly found in axial flow pumps, blowers, and compressors. A second plurality of energy adding blades, which may be referred to as auxiliary blades, is provided and is positioned downstream from the main blades without intervening stationary vanes and may be located either directly behind corresponding main blades or may be circumferentially displaced forward or backward in the direction of blade travel. The leading edges of the auxiliary blades are angled with respect to, or are not parallel, to the trailing edges of the main blades. The blades are warped or twisted from a root cross section that exhibits a chord forming an angle of greater than 90 with the plane of rotation of the blades. The trailing edge of the auxiliary blades at the respective blade roots is thus placed away from the main blades and points into the direction of rotation.

3 Claims, 6 Drawing Figures 1 HIGH ENERGY AXIAL FLOW TRANSFER STAGE This application is a continuation-in-part of my copending application Ser. No. 183,413, filed Sept. 24, 1971, entitled High Energy Axial Flow Transfer Stage now abandoned.

The present invention pertains to axial flow apparatus, and more particularly, to apparatus for imparting high energy to a fluid.

In axial flow compressors, pumps, and blowers, energy is imparted to the fluid through the relative motion of the fluid and the blades mounted on and rotating with a rotor. Energy transfer can be controlled therefor by both blade design as well as blade velocity. To impart substantial energy to a fluid, different blade designs have been utilized and blade classifications, such as reaction blades or impulse blades, have resulted. The advantages and limitations of these two types of blade designs are discussed in my US. Pat. No. 3,291,381, wherein I teach the design of a compact impeller-blade giving impulse-type energy transfer at the hub and reaction-type energy transfer in the outer parts of the blades.

The impeller design described by me in the above patent permits the apparatus to impart a greater energy to the fluid than previously possible; however, the utilization of an impeller or blade having an impulse configuration of crescent shape at the hub and a reaction configuration at the tip, while effective, presents other problems. Specifically, the crescent shape near the hub, and the transition thereof to the outer sections, brings about air pockets which result in undesirable flow patterns under certain operating conditions; further, the manufacturing technique may be quite involved.

It is therefore an object of the present invention to provide an axial flow stage for imparting high energy to a fluid.

It is another object of the present invention to provide an axial flow stage that, while capable of high energy transfer to a fluid, nevertheless incorporates relatively simple blade design.

It is a further object of the present invention to provide an axial flow stage having greater flexibility in its design for the purpose of obtaining a wider range of efficient performance while maintaining higher energy transfer.

It is still a further object of the present invention to provide, at any given radial distance from the rotor axis, blade sections of the main and auxiliary blades that cooperate while providing freedom in the circumferential and axial spacing between the first and second plurality of blades.

It is yet a further object of the present invention to provide an axial flow apparatus capable of high energy transfer utilizing two sets of blades, the leading edges of each set of blades being axially displaced from the leading edges of the outer set while the trailing edges of the first set are non-parallel to the leading edges of the second set, the second set of which operate as auxiliary blades and rotate in unison with the first set of blades.

It is still another object of the present invention to provide an axial flow stage capable of high energy transfer to a fluid wherein auxiliary blades are utilized to increase the energy transfer of the stage without the use of high and inefficient blade speeds.

These and other objects of the present invention will become apparent to those skilled in the art as the description thereof proceeds.

Briefly, in accordance with the embodiment chosen for illustration, an axial flow stage is provided incorporating a first set of blades, which I shall call the main blades, that are mounted upon a rotor or hub and ex-' tend radially therefrom to a housing forming an axial passageway between the rotor and housing. The main blades may be formed of conventional airfoil shape of the type found in compressors, pumps, and blowers and are warped or twisted from the root to the tip. A set of auxiliary blades is positioned downstream from the main blades without intervening stationary vanes; each auxiliary blade is also of conventional or foil-like cross section.

The auxiliary blades at the hub or root are positioned relative to the plane of rotation of the blades such that a line extending from the blade tip to the trailing edge forms an angle of greater than with the plane; further, the auxiliary blades always exhibit a trailing edge at the root that points into the direction of rotation.

The present invention may more readily be described by reference to the accompanying drawings, in which:

FIG. 1 is a front elevational view of an axial flow stage constructed in accordance with the teachings of the present invention.

FIG. 2 is a cross-sectional view of the apparatus of FIG. 1.

FIG. 3 shows successive cross sections of a main blade of the apparatus of FIGS. 1 and 2.

FIG. 4 shows successive cross sections of an auxiliary blade of the apparatus of FIGS. 1 and 2.

FIG. 5 is a top view of a main blade and a auxiliary blade showing the non-parallel relationship of the trailing edge of the former relative to the leading edge of the latter.

FIG. 6 is a perspective view of the apparatus of the present invention, without the housing, showing the re lationship between the main and auxiliary blades.

Referring now to the drawings, the apparatus of the present invention contemplates the utilization of a housing 10 in which a rotor 11 is mounted; the rotor and housing are coaxial to thereby define an axial flow passageway 14 therebetween. The rotor 11 supports a first plurality of blades 15 which may be referred to as main blades. Each of these extend radially from its root section 17 at the rotor 11 to a point at its tip 18 adjacent the inner wall 19 ofthe housing 10. The blades l 5 are circumferentially spaced about the rotor and incorporate a conventional airfoil-like section to be described more fully hereinafter.

Axially displaced from the main blades 15 is a second plurality of blades 20 which may be referred to as auxiliary blades. There are no stationary vanes between the main and auxiliary blades. The blades 20 also extend from their respective root sections 21 at the rotor 11 to a tip portion 22 which may or may not be adjacent the inner wall 19 of the housing 10. In the embodiment chosen for illustration, both the main blades and the auxiliary blades are fixed in their respective positions relative to each other as shown; it will be apparent to those skilled in the art that the respective blades may be made adjustable in their circumferential, axial, and pitch positions. The auxiliary blades may be circumferentially displaced relative to the main blades and the leading edges 23 of the auxiliary blades 20 may be positioned ahead of the trailing edges 24 of the main blades 15; however, it may be seen that trailing edges 24 are angled with respect to, or are not parallel to, the leading edges 23. The non-parallel relationship of the leading edges 23 and trailing edges 24 may be stated differ ently; for example, the leading edges 23 of the auxiliary blades are displaced relative to the trailing edges 24 of the main blades, in the circumferential direction, in such a way that the distance between the two edges changes as the blades extend radially. The rotor may be constructed to permit axial and circumferential displacement of the main and auxiliary blades relative to each other.

With specific reference to FIG. 3, the successive cross sections of the main blades 15 is shown. The direction of blade travel is indicated by the arrow 25 while the cross section of the blade 15 at the hub 11 is indicated at 27. The blade is warped as it extends radially from the hub as may be seen by the cross section 29 at the approximate midpoint and the cross section 31 at the blade tip. Lines 27a, 29a, and 31a have been drawn from the leading to the trailing edges of the cross sections 27, 29 and 31 respectively. A line 30 is provided to represent an imaginary plane of rotation of the blade 15; the line 30 has been displaced to the right in FIG. 3 to facilitate the following description of the angular relationships involved. It may be seen that the cross section 27 has a line 27a extending from the tip to the trailing edge that forms an angle with the imaginary plane of rotation 30. As the blade extends from the root to the area of the cross section 29, the line extending from the tip to the trailing edge thereof 29a blades and incorporates an airfoil-like cross section throughout its length. The cross section 32 adjacent the hub 11 includes a trailing edge that points into the direction of travel of the blade. The blade 20 is warped as it extends radially outwardly from the hub as evidenced by the cross section 34 at the approximate midpoint thereof and the cross section 36 at the blade tip. As mentioned previously, the auxiliary blade 20 may be foreshortened and need not extend to a position adjacent the inner wall 19 of the casing 10. Lines 320, 34a, and 36a have been drawn from the leading to the trailing edges of the cross sections 32, 34, and 36 respectively. A line 40 is provided to represent an imaginary plane of rotation of the auxiliary blade 20; the line 40, similarly to line 30 in the previous figure, has been displaced to the right to facilitate the description of the angular relationship of the blade cross sections. The root cross section 32 includes a trailing edge that points substantially into the direction of travel of the blade as indicated by the arrow 25. The line 32a drawn from the leading to the trailing edges of the cross section 32 forms an angle 4) with the imaginary plane 40. It may be noted that the angle (1) is greater than 90. The line 34a forms an angle 4) with the plane 40 while the line 36a forms an angle (1) with the plane 40. It may be seen that the angle (1) decreases as the blade is twisted or warped as it extends from its root to its tip.

Referring now specifically to FIGS. 4 and 5, the relationship of the main blades 15 and auxiliary blades 20 is shown with greater clarity. In this embodiment chosen for illustration, it may be seen that the auxiliary blades 20 have been shifted circumferentially with respect to the main blades 15; further, the non-parallel relationship of the trailing edges 24 of the main blades 15 and the leading edges 23 of the auxiliary blades 20 is specifically shown in FIG. 5. As mentioned previously, the main blades 15 are of conventional design and are generally of the reaction type blades commonly found in axial flow pumps, blowers and compressors. The auxiliary blades 20 each include conventional airfoil sections but are warped with the cross section of the blade adjacent the rotor 11, or root section, having the trailing edge extend into the direction of rotation of the rotor. The auxiliary blades are designed to yield impulse-type energy transfer to the fluid flowing through the stage. The auxiliary blades may be foreshortened and extend radially from the rotor 11 for a length short of the distance from the rotor to the housing. In operation, the main and auxiliary blades are fixed on the rotor 11 with respect to each other and therefore rotate in unison without relative movement; further, no stationary vanes are positioned between the'main and auxiliary blades, although such stationary vanes may be placed upstream or downstream of the stage.

The sections of the auxiliary blades in any one particular radial distance from the rotor axis are cooperative with the corresponding sections of the main blades, but the blades as a whole are independently shaped with the leading edges of the auxiliary blades non-parallel with the trailing edges of the main blades; that is, the distance between the leading and trailing edges of the auxiliary and main blades respectively, measured in a circumferential direction, varies as the blades extend radially from the hub.

It will be obvious to those skilled in the art that stationary vanes will be placed in the axial flow passageway 14; the stationary vanes may be placed either ahead of or downstream of the main and auxiliary blades or perhaps may be placed in both positions but are not placed between the main and auxiliary blades. Energy transfer is essentially proportional to the velocity component in the peripheral direction which is created by the action of an impeller of the fluid machine. This energy transfer relationship exists notwithstanding the utilization of stationary vanes in the apparatus.

The utilization of main and auxiliary blades as described permits great values of such peripheral velocity components to be created; the energy transfer substantially exceeds that transfer available in the present devices of the same dimensions and same rotor rotational velocities. The present design also permits great flexibility in the choice of the distribution of rotary components over the radial distance between the rotor and the housing.

The cross sections of all blades referred to herein are essentially airfoil shaped. Generally, the term airfoil refers to cross sections widely used in aeronautics as well as in flow machinery design. These cross sections form elongated shapes with a thickness small by comparison to their length and with generally round leading edges with relatively sharp trailing edges. The thickness of the cross section gradually increases from the leading edge to a point somewhere between one-fourth and one-half of the length from the leading edge and then gradually diminishes toward the trailing edge. The configuration of the surrounding environment as well as a variety of conditions of the fluid flow will dictate the final shape of the airfoil. In certain applications, it may be possible to substitute planar sheets of construction material for the airfoils of greater thickness, for the sake of construction economy, in which case the warped sheets would have the shape of the center sections of corresponding airfoils. Therefore, as referred to herein, the term airfoil means the commonly accepted configuration of an airfoil as well as the simulated or approximated airfoil discussed above.

I claim:

1. In a fluid flow apparatus including a rotor, the axis of which extends along the direction of fluid flow, and having a housing surrounding said rotor, said housing extending along said rotor and radially spaced therefrom to define a fluid passageway between said rotor and housing a fluid energy boosting stage comprising:

a first plurality of circumferentially spaced energy adding blades secured to said rotor for movement in a plane of rotation, each having a leading edge and a trailing edge and each extending radially therefrom to adjacent said housing; each of said first plurality of blades having substantially airfoil sections with the section at the blade root positioned relative to the plane of rotation of said blades such that a line extending from the leading to the trailing edge forms an angle with the plane of rotation that becomes progressively 1 less at cross sections further from the blade root; a second plurality of circumferentially spaced energy adding blades secured to said rotor for movement in a plane of rotation, each having a leading edge and a trailing edge and each extending radially therefrom for rotation with said first plurality of blades said second plurality of blades being substantially circumferentially displaced from said first plurality of blades; each of said second plurality of blades shaped and positioned independently from said first plurality of blades and having substantially airfoil sections, said sections at any given radial distance from the rotor axis cooperating with. corresponding sections of the first plurality of blades to deflect the fluid flowing through the apparatus, the section of each of said second plurality of blades at the blade root adjacent said rotor positioned relative to the plane of rotation of said blades such that a cord line extending from the leading to the trailing edge forms an angle of greater than with the plane, with the trailing edge pointing toward the direction of rotation of the blade, said angle becoming progressively less at sections further from the blade root. the trailing edges of said first plurality of blades being angled with respect to the leading edges of said second plurality of blades. 2. The combination set forth in claim 1, wherein said first and second pluralities of circumferentially spaced blades are positioned with the leading edges of said first plurality axially displaced from the leading edges of said second plurality and with said first and second pluralities of blades circumferentially displaced relative to each other.

3. The combination set forth in claim 1, wherein each i of said first plurality of blades extends radially from said rotor to adjacent said housing and wherein each of said second plurality of blades extends radially from said rotor and is shorter from its root to its tip than each of said first plurality of blades.

* l= l= l= 

1. In a fluid flow apparatus including a rotor, the axis of which extends along the direction of fluid flow, and having a housing surrounding said rotor, said housing extending along said rotor and radially spaced therefrom to define a fluid passageway between said rotor and housing a fluid energy boosting stage comprising: a first plurality of circumferentially spaced energy adding blades secured to said rotor for movement in a plane of rotation, each having a leading edge and a trailing edge and each extending radially therefrom to adjacent said housing; each of said first plurality of blades having substantially airfoil sections with the section at the blade root positioned relative to the plane of rotation of said blades such that a line extending from the leading to the trailing edge forms an angle with the plane of rotation that becomes progressively less at cross sections further from the blade root; a second plurality of circumferentially spaced energy adding blades secured to said rotor for movement in a plane of rotation, each having a leading edge and a trailing edge and each extending radially therefrom for rotation with said first plurality of blades said second plurality of blades being substantially circumferentially displaced from said first plurality of blades; each of said second plurality of blades shaped and positioned independently from said first plurality of blades and having substantially airfoil sections, said sections at any given radial distance from the rotor axis cooperating with corresponding sections of the first plurality of blades to deflect the fluid flowing through the apparatus, the section of each of said second plurality of blades at the blade root adjacent said rotor positioned relative to the plane of rotation of said blades such that a cord line extending from the leading to the trailing edge forms an angle of greater than 90* with the plane, with the trailing edge pointing toward the direction of rotation of the blade, said angle becoming progressively less at sections further from the blade root. the trailing edges of said first plurality of blades being angled with respect to the leading edges of said second plurality of blades.
 2. The combination set forth in claim 1, wherein said first and second pluralities of circumferentially spaced blades are positioned with the leading edges of said first plurality axially displaced from the leading edges of said second plurality and with said first and second pluralities of blades circumferentially displaced relative to each other.
 3. The combination set forth in claim 1, wherein each of said first plurality of blades extends radially from said rotor to adjacent said housing and wherein each of said second plurality of blades extends radially from said rotor and is shorter from its root to its tip than each of said first plurality of blades. 